Weight compensation devices are provided on a robot, so that the motors for the individual elements only carry out the movement work and only have to compensate to a limited extent or not at all forces and torques caused by gravitation. This more particularly applies to the rocker of a robot and its movement about the horizontal A2 axis relative to the robot carrousel and base.
Weight compensation devices have been provided with or proposed to have counterweights, mechanical springs, fluid springs in the form of pneumatic and hydraulic cylinders with pistons movable axially therein, magnetic systems, as well as lever and cable systems.
Each of the known weight compensation devices suffers from disadvantages. Thus, counterweights require a large amount of space and also increase the mass and inertia of the overall robot. Mechanical springs are relatively large if they are to apply the necessary forces and consequently have a considerable size. Fluid springs are not maintenance-free and may require the connection to a pressure medium, e.g. in a pressure container. Lever and cable systems are complicated and costly. Magnetic systems are also relatively large.
The problem of the invention is to provide a weight compensation device which both avoids the aforementioned disadvantages and requires little space and has a low weight and more particularly ensures a high flexibility in use.